Multi-layer golf ball having improved inter-layer adhesion via induction heating

ABSTRACT

This invention is directed to golf balls having at least two adjacent layers, wherein a coating layer of metal materials is on at least one surface of the adjacent layers. The adhesion of the adjacent layer is improved by induction heating. The invention also is directed to ink solution for golf equipment comprising metal materials that can improve adhesion of the ink to the golf equipment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/028,054, filed on Jan. 3, 2005, the entire disclosure of which ishereby incorporated herein by reference.

FIELD OF THE INVENTION

This invention is related to multi-layer golf balls, wherein theadhesion between at least two adjacent layers is improved by inductionheating.

BACKGROUND OF THE INVENTION

Conventional golf balls include multi-layer balls, which may have one ormore wound layers. The difference in playing characteristics issignificant among the three different types of balls: two-piece balls,wound balls and multi-layer balls. Two-piece balls are typically madewith a single solid core encased by a cover material. These balls aregenerally most popular among recreational golfers, because they aredurable and provide maximum distance. Typically, the solid core is madeof polybutadiene chemically cross-linked with zinc diacrylate and/orsimilar cross-linking agents. The cover material comprises tough,cut-proof blends of one or more ionomers, such as SURLYN® soldcommercially by DuPont or IOTEK® sold commercially by Exxon.

Wound balls typically have either a solid rubber or liquid-filledcenter, around which many yards of a stretched elastic thread or yarnare wound to form a core. The wound core is then covered with a durableionomer cover, or a softer cover such as balata or polyurethane. Woundballs are generally softer than two-piece balls and can provide morespin, thus enabling skilled golfers to have more control over the ball'sflight and placement.

Solid multi-layer golf balls may have one or more core layers, one ormore intermediate layers and one or more cover layers. They are designedto overcome some of the undesirable features of conventional two-pieceballs, such as hard feel, while maintaining the positive attributes ofwound balls, such as increased initial velocity and distance. It is alsodesirable that multi-layer balls have similar “click and feel” and spincharacteristics of wound balls.

Solid multi-layer golf balls can be produced using a variety ofmanufacturing techniques. For example, two or more cover layers may bemolded around a conventional core with one or more intermediate layersinterposed between the cover layers and the core. Alternatively,multi-layer balls may be formed from cores having more than one corelayers and may optionally contain one or more intermediate and/or coverlayers. Multi-layer balls may even comprise a conventional wound corearound which at least one intermediate layer and/or at least one coverlayer are formed. Typically, the outer layers of multi-layer golf ballsare formed by molding them around the core or the preceding intermediatelayer or cover layer. Conventional techniques for applying such layersinclude injection molding, compression molding and casting the layermaterial around the preceding core or layer.

It is desirable to obtain good adhesion between the various solidlayers. If the adhesion between the layers is not acceptable, theperformance or durability of the golf ball can be adversely affected.For example, poor adhesion can cause unattached areas to form betweenthe layers that can result in separation of the layers when the ball isstruck with a club. It is also known that the adhesion between the woundlayer and the encasing layer can be improved when the encasing materialflows into the voids among the windings during the molding process,resulting in improved adhesion.

The patent literature discloses a number of references teaching improvedadhesion techniques. U.S. Pat. Nos. 6,103,166, 6,342,019, and 6,648,776to Boehm et al., which are incorporated by reference in theirentireties, relate to using textured surface profile that are integrallymolded to the outer surface to improve adhesion between golf balllayers. The surface profile comprises peaks having heights between about2 mils and about 15 mils.

U.S. Pat. No. 6,440,346 to Wai et al. relates to a golf ball comprisinga core having outwardly extending projections, and an interstitial spacelayer of relatively less resilient material applied in the interstitialspace between the projections on the surface of the core. A cover isthen applied over the core and the interstitial space layer.

U.S. Pat. No. 6,605,243 to Masatani relates to a method of producinggolf ball comprising a spherical elastic inner layer having outwardlyextending projections with either round or polygonal shapes, and athermoplastic resin outer layer covering the inner layer.

U.S. Pat. No. 6,761,846 to Murphy relates to a method of making a golfball with an interior layer having outwardly extending protrusions tofacilitate adhesion to the cover materials.

U.S. Pat. No. 5,837,183 to Inoue et al. relates to a method of moldinggolf ball comprising the steps of providing a thin film layer of amagnetic material on the inside surface of a spherical cavity of a mold,embedding an induction heating coil and a cooling channel beneath themagnetic material in the mold, generating a magnetic field via a highfrequency oscillator to heat the cavity, introducing a predeterminedamount of a molten stock material to fill the cavity, and feeding acoolant via the cooling channel to complete the molding process.

U.S. Pat. No. 6,585,607 to Tzivanis et al. relates to a process toincrease adhesion between two adjacent layers in a golf ball comprisingthe steps of roughening the bonding surface of one layer, chlorinatingthe roughened surface, treating the surface of adjacent layer with asilicone-based adhesion promoter, and joining the layers.

However, there remains a need to improve interlayer adhesion in theprocess of making multi-layer golf balls.

SUMMARY OF THE INVENTION

This invention is directed to a multi-layer golf ball comprising atleast two layers, and one of the layers comprises a plurality ofsusceptors. The susceptors when exposed to induction heating improve theadhesion between the layers. The susceptors are preferably metals, morepreferably magnetic and most preferably ferromagnetic materials.Suitable susceptors include iron, iron-containing compounds, cobaltnickel, strontium, gadolinium, SrFe₁₂O₁₉, CO₂Ba₂Fe₁₂O₂₂, Fe₃O₄ (44micron), Fe₃O₄ (840 micron), Fe₂O₃, iron base steel stocks (e.g. S45C,and S55C) and prehardened steel stocks (e.g. NAK steel). The layerscontaining susceptors may further comprise non-magnetic fillers, fibers,flakes, filaments, metal, ceramic, graphite, glass, boron, or Kevlar.

The susceptors can be in the form of a continuous polygonal mesh, suchas triangle, square, pentagon, hexagon, and quadrilateral. In addition,the susceptors can be in the form of discrete fillers, short fibers,long fibers, flakes, spheres, microparticles, nanoparticles,nanotubules, or nanocapsules.

In one embodiment, the susceptors are mixed with a thermoplasticpolymeric matrix, or a thermosetting polymeric matrix. The mixture canbe applied to at least one surface of the adjacent layers beforeinduction heating is applied.

In another embodiment, the susceptors are added to a castable layer,such as polyurea, polyurethane or a staged resin film or material,before induction heating is applied to cure the castable layer.Furthermore, the susceptors can be added to a layer adjacent to thecastable layer before induction heating is applied to indirectly curethe castable layer.

In another embodiment, the golf ball comprises a thermoplastic layercontaining a heat-reactive material and susceptors. The heat-reactivematerial reacts with itself or with the thermoplastic layer upon theinduction heating. Alternatively, a moisture barrier layer containingsusceptors is formed between the cover layer and the core layer, whichis cured by induction heating. Furthermore, due to the relatively highspecific gravity of some ferromagnetic susceptors, the susceptors canform a portion of a thin dense layer of a perimeter-weighted golf ball.

In a different aspect, the invention is directed to an ink solutioncomprising susceptors. The ink can be applied to sports equipment, suchas game balls, golf ball, golf club, golf glove, golf shoe, golf bag,and golf accessories.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a)-1(h) illustrate a continuous or screen mesh made fromsusceptors.

FIGS. 2( a)-2(c) illustrate discreet placements of susceptors.

FIGS. 3( a)-3(d) illustrate examples of metal susceptors.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a multi-layer golf ball having oneor more core layers, one or more intermediate layers, and/or one or morecover layers, wherein at least one layer contains a metal material(“MM”), and wherein the adhesion between two adjacent layers is improvedvia induction heating (“IH”) of the MM. The present invention is alsodirected to the selective use of MM in golf ball core and/or coverlayers to allow for temperature-controlled IH for adhering or bonding,cross-linking, improving durability, etc. as outlined herein. Analternative embodiment is directed to an ink indicia comprising MM forimproved durability via a printing of the mark on golf balls or golfequipment.

The basic components of an IH system comprise an induction coilconnected to an alternating current (“AC”) source, and a work piece thatis to be heated. The induction coil generates a magnetic fieldsurrounding the work piece that contains MM susceptors. The magneticfield induces eddy currents in the MM susceptors within the work piece,and thus resulting in fast, clean, localized and consistent heatingwithout physical contact between the coil and the work piece. See U.S.Pat. No. 6,056,844 to Guiles et al. and “Ameritherm Inc.'s InductionHeating Applications and Equipment Selection Guide” atwww.ameritherm.com and web pages contained therein (“Ameritherm”), bothof which are incorporated by reference in their entireties.

When IH is applied to a work piece, the frequency of the AC in theinduction coil is inversely proportional to the depth that the magneticfield penetrates the work piece. For example, low AC frequencies ofabout 5 KHz to about 30 KHz are effective for heating relatively thickermaterials. Higher AC frequencies of about 100 KHz to about 400 KHz areeffective to penetrate smaller or shallower parts. AC frequencies of upto about 60 MHz are suitable for microscopic parts.

IH can be applied to work pieces that are made of magnetic orelectrically conductive materials. To apply IH to non-conductive orplastic work pieces, susceptors made of conductive metal materials canbe used to transfer heat by conduction or radiation to thenon-conductive or plastic work pieces. Different conductive metalmaterials react differently to induced electric current. For instance,because carbon, steel, tungsten and tin have relatively high electricalresistivities, these materials can be heated more quickly than thosematerials with low electrical resistivities.

According to their characteristics under a magnetic field, the MM can befurther divided into diamagnetic, paramagnetic and ferromagneticmaterials. Diamagnetic materials such as copper, silver, and gold haveweak and negative susceptivitiy toward magnetic forces. They areslightly repelled by a magnetic field and do not retain any magneticproperty once the magnetic field is removed. See “Diamagnetic,Paramagnetic, and Ferromagnetic Materials,” available athttp://www.ndt-ed.org/EducationResources/CommunityCollege/MagParticle/Physics/MagneticMatls.htm.Paramagnetic materials such as magnesium, molybdenum, lithium andtantalum have small and positive susceptivity toward magnetic forces.Paramagnetic materials are slightly attracted to a magnetic field but donot retain any magnetic property once the magnetic field is removed.Ferromagnetic materials (“FMMs”) such as iron, nickel and cobalt havehigh susceptivity to magnetic fields and exhibit a strong attraction tomagnetic fields. They retain their magnetic properties after theexternal field is removed.

When applying IH, FMMs are easier to heat than non-magnetic materials,because they naturally resist the rapidly changing magnetic fieldsproduced by the AC within the induction coil. The resulting frictionproduces heat known as hysteresis heating, in addition to the heatgenerated by eddy currents. When an FMM is placed in an electromagneticfield, the hysteresis losses in the material cause its temperature torise, eventually reaching its Curie temperature. Curie temperature isdefined as the temperature at which ferromagnetism in an FMM disappearsas thermal oscillations overcome the orientation due to exchangeinteraction, resulting in a random grouping of the atomic particles.Upon reaching its Curie temperature, the material crystal latticeundergoes a dimensional change, causing a reversible loss of magneticdipoles. Once the magnetic dipoles are lost, the ferromagneticproperties cease, thus halting further heating.

In the present invention, the IH process is applied to improveinterlayer adhesion in multi-layer golf balls by optimizing susceptordesign, fusion bonding or welding of thermoplastic layers. Preferably,FMMs or other materials amenable to induction heating can be used aloneor in conjunction with FMMs. Suitable FMMs are discussed in U.S. Pat.Nos. 5,837,183 to Inoue et al., and 6,056,844 to Guiles et al., whichare incorporated by reference in their entireties. Examples of suitableFMM include, but are not limited to, CO₂Ba₂Fe₁₂O₂₂, Fe₃O₄ (44 micron),Fe₃O₄ (840 micron), Fe₂O₃, SrFe₁₂O₁₉, iron, cobalt, nickel, the rareearth elements including lanthanum, cerium, praseodymium, neodymium,promethium, samarium, europium, gadolinium, terbium, dysprosium,holmium, erbium, thulium, ytterbium, and lutetium, the actinide elementsincluding actinium, thorium, protactinium, uranium, neptunium,plutonium, americium, curium, berkelium, californium, einsteinium,fermium, mendelevium, nobelium, lawrencium, iron containing compoundssuch as iron based steel stocks, e.g. S45C and S55C, and prehardenedsteel stocks, e.g. NAK steel. In addition, “nanofoam,” an allotrope ofcarbon, is ferromagnetic and can be used as susceptor in the invention.See “Nanofoam Exhibits Surprising Magnetic Properties,” available athttp://www.pa.msu.edu/˜tomanek/publicity/magfoam-14may04.html.

Referring to FIGS. 1( a), 1(b), 1(c), 1(d), 1(e) 1(f), 1(g) and 1(h),susceptors made of MM can be a continuous network such as a screen meshpositioned between at least two adjacent layers. Alternatively, the MMmay be selectively placed within, on or near the surface of a layersubject to induction heating. As shown, the continuous network can be amesh of polygons, such as hexagons (50), squares (52), quadrilaterals(54), and triangles (56), or a mesh of an interconnected network ofcircles (58), or a network of meridians (60). The cut away (62) showsthe continuous network of MM located within a layer in the golf ball.The expanded view (64) shows the MM as continuous filament or fiber(65). The continuous network can also be a filament fiber that is wound,wrapped, or in the form of a mesh or screen.

Alternatively, the MM susceptors may be present as an intermediate layerwith non-uniform thickness, wherein the layer comprises a plurality ofouter projections disposed on the outer surface of said intermediatelayer. As discussed in U.S. Pat. No. 6,733,364, which is incorporatedherein in its entirety, the outer projections may have any shape orprofile, including but not limited to, trapezoidal, sinusoidal, dome,dome, stepped, cylindrical, conical, truncated conical, rectangular,pyramidal with polygonal base, truncated pyramidal, polyhedronal, andthe like.

Referring to FIGS. 2( a), 2(b) and 2(c), the MM susceptors can be adiscrete network of big circles (70), or small circles (72). MMsusceptor (82) is part of a multi-layer ball (74) comprising a core(76), an inner cover (78), and an outer cover (80). The MM susceptorsmay be located between the inner cover (78) and the core (76). The MMsusceptors may be discrete filler, short or long fiber, flake, sphere,micro or nanoparticle, nanotubule, nanocapsule, etc. of uniform orirregular shape.

Referring to FIGS. 3( a), 3(b), 3(c) and 3(d), the MM susceptors can bein various shapes. For example, susceptor (84) has a ball (86) and rod(88) construction. In the alternative, a susceptor can be a mushroom(90) and rod (91) configuration, an anchor (92) and rod (93)configuration, or a ball (94) and webbed legs (96) construction. Thesusceptors in these figures can be embedded into the core.

Any of the embodiments herein may additionally include non-magneticfillers, fibers, flakes, filaments, metal, ceramic, graphite, glass,boron, Kevlar, etc. such as those of 6,142,887, 6,494,795, 6,595,874,and 5,783,293, which are incorporated herein by reference in theirentireties.

Alternatively, a paste, a coating, or an adhesive comprising MMsusceptors in a thermoplastic or thermosetting polymeric matrix orcarrier may be applied as a thin layer to at least one surface of theadjacent layers and then induction heated to form strong adhesionbetween adjacent layers.

The same approach is applicable to the curing of thermosettingmaterials, such as polyurethane or polyurea wherein MM susceptors areadded to a castable polymer and then induction heated to thermally curethe polymer. Alternatively, a layer under or over the PU or polyurea maycomprise MM susceptors and the PU or polyurea may be cured indirectlyvia heat transfer from the layer comprising MM susceptors to the PU orpolyurea layer. Good adhesion between these layers can improve moistureresistance of the PU or polyurea by providing a non-hygroscopic fillerand/or tortuous-path scenario, depending upon the choice of type andmorphology of magnetic material employed.

Alternatively, the MM susceptors can also be utilized with multi-layergolf balls having at least one portion that is formed from a partiallycured thermosetting resin composition, which is also known as a stagedresin film (“SRF”). As described in U.S. Pat. App. Pub. 2003/0027667,which is incorporated herein in its entirety, an SRF includes at leastone cross-linkable resin. Examples of cross-linkable resin includes, butare not limited to, polyurethane, polyurea, epoxy, diene rubber,unsaturated polyester, silicone, interpenetrating polymer network, orany combination thereof. The polyurethane and polyurea may be derivedfrom a partially or totally blocked polyisocyanate. The SRF should beflexible enough that it will not readily fracture or degrade fromordinary use. The SRF preferably is in the form of a malleable sheet forease of handling and processing, and the SRF may be supported by asubstrate or fabric from which it can be readily peeled from which itcan be readily peeled from just prior to molding over a portion of thegolf ball. The substrate or fabric may also remain attached to the SRFand become incorporated into the multi-layer golf ball. In oneembodiment, the SRF may be part of a laminate sandwiched between twolayers of a cross-linkable, uncured or partially cured sheet ofpolybutadiene rubber formulation. The SRF can be cured by the heat thatcan be generated when the MM susceptors in the vicinity is inductionheated.

In a separate embodiment, an ink or other coating containing MMsusceptors may be used to provide a durable marking for golf balls. Forexample, the ink is applied in a conventional manner and then isinduction heated to cause the marking to become embedded or otherwisefirmly locked into the cover or core layer. This can be used for theapplication of logo or indicia to a thermoplastic cover layer such as anionomer. In addition, it may also be used with thermoset layers, wherethere can be a chemical link between the ink and the substrate via aheat induced reaction between the ink and the thermoset substrate.Alternatively, by simply softening the thermoset substrate, a betterphysical linkage between the ink and the substrate can be achieved. Theuse of appropriate ink chemistries may facilitate the “sublimation” ofthe marking into the substrate.

Alternatively, an ink solution can comprise a susceptor, or a pluralityof susceptors, and the ink solution can be applied to sports equipment,such as game balls, golf ball, golf club, golf glove, golf shoe, golfbag, and golf accessories. The susceptor improves the adhesion betweenthe ink solution and the sports equipment when induction heating isapplied.

In another embodiment, a thermoplastic core or cover component with MMsusceptors is further modified with a heat-reactive material, such thatwhen the layer is induction heated it causes the reaction of thepre-embedded or pre-mixed material either with itself or with thethermoplastic material to result in improved cross-linking orpolymerization. For example, a polyolefinic polymer is mixed with a hightemperature peroxide and any number of coagents (ZDA, TMPTA, etc.) suchthat there is little or no reaction as the core and/or cover layer ismolded but that following molding, the core/cover is induction heatedcausing a polymerization/cross-linking to occur. Preferably, the polymerhas some unsaturation (such as EPDM, PBR, etc.), but it may also be asaturated polymer such as a metallocene catalyzed ethylene copolymerthat is susceptible to hydrogen abstraction and subsequentperoxide-initiated cross-linking.

In another embodiment, an MM layer is a moisture barrier layer betweencore and cover layers, wherein the moisture barrier layer improvesadhesion between the layers. Moisture barrier layers are disclosed inU.S. Pat. App. Pub. 2003/0114247 and patent documents cited therein. Themoisture barrier layer is preferably applied as a spray, dip, or spin,etc. in a very thin coating or layer so as not to otherwise affect golfball properties.

In any of these embodiments, where the specific gravity of the magneticmaterial is high, i.e., greater than about 2.0, such layer may be a thindense layer. See U.S. Pat. App. Pub. 2002/0173382 and related patent andpatent applications, and see U.S. Pat. App. Pub. 2004/0219995 regardinginter-cross-linked layers. The present invention may also be used withany of the selectively weighted golf balls discussed in U.S. Pat. No.6,595,874.

In one embodiment of the invention, the multi-layer golf ball comprisesa core, an intermediate layer, and a cover layer, wherein the golf ballhas an overall size of about 1.68 inches to about 1.8 inches. The golfball has an Atti compression of about 100 or less than about 100,preferably about 40 to about 120.

The core has a diameter from about 0.25 inch to about 1.65 inches,preferably from about 1.25 inches to about 1.65 inches. The core has ahardness of at least about 15 Shore A, preferably about 50 Shore A toabout 90 Shore D, and more preferably about 35 Shore D to about 60 ShoreD. The core has an Atti compression of 80 or less than 80, preferablyabout 10 to about 70.

The core may comprise an inner core layer and an outer core layer,wherein the inner core layer has a diameter of about 0.25 inch to about1.62 inches, preferably about 0.50 inch to about 1.60 inches. The outercore layer has a thickness of at least about 0.1 inch, preferably about0.10 inches to about 0.8 inch.

The intermediate layer has a thickness of about 0.002 inch to about 0.1inch, preferably about 0.01 inch to about 0.045 inch. In a differentembodiment, the intermediate layer is a moisture barrier layer having amoisture vapor transmission rate that is less than the moisture vaportransmission rate of the cover layer. The intermediate layer has ahardness of about 30 Shore D or greater, preferably about 90 Shore D orless, and more preferably about 55 Shore D to about 65 Shore D.

The cover layer has a thickness of about 0.02 inch to about 0.12 inch,preferably about 0.02 inch to about 0.05 inch. The cover layer has ahardness of about 20 Shore D to about 70 Shore D.

The core of the multi-layer golf ball can be made either from (a) athermoplastic highly neutralized polymer (“HNP”) such as those disclosedin U.S. Pat. App. Pub. 2003/0013549, 2003/0144087, 2003/0158352, and2003/0181260, and U.S. Pat. Ser. Nos. 10/882,130, 10/958,000 and10/959,751, or (b) a thermosetting rubber such as a polybutadiene, ZDA,peroxide, and cis-to-trans catalyst such as a halogenated organosulfurcompound, such as those formulations disclosed in, U.S. Pat. No.6,162,135, U.S. Pat. App. Pub. 2003/0064826, and U.S. application Ser.Nos. 10/882,130 and 10/958,000. These references are incorporated byreference in their entireties.

The thermoplastic HNP, is formed from a reaction between acid groups ona polymer, a suitable source of cation, and an organic acid or thecorresponding salt. The suitable source of cation is present in anamount sufficient to neutralize the acid groups on the polymer by atleast about 80%. In a preferred embodiment, the acid groups on thepolymer may be neutralized by at least about 90%. In another preferredembodiment, the acid groups on the polymer may be neutralized by about100%.

The HNP may further comprise partially neutralized ionomeric copolymers,ionomeric terpolymers, ionomer precursors, thermoplastics, thermoplasticelastomers, grafted metallocene-catalyzed polymers, non-graftedmetallocene-catalyzed polymers, single-site polymers, highly crystallineacid polymers and ionomers thereof, cationic ionomers and mixturesthereof.

Examples of organic acid of the HNP include, but are not limited to, analiphatic organic acid, an aromatic organic acid, a saturatedmono-functional organic acid, a saturated di-functional organic acid, asaturated multi-functional organic acid, an unsaturated mono-functionalorganic acid, an unsaturated di-functional organic acid, an unsaturatedmulti-functional organic acid, and a multi-unsaturated mono-functionalorganic acid.

Suitable cations can be used to neutralize the acid groups of the HNP.Examples of suitable cations include, but are not limited to, barium,lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium,strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver,aluminum, tin, or calcium.

Alternatively, salts of fatty acids can be used to neutralize theorganic acids of the HNP. These fatty acids include, but are not limitedto, caprioic acid, caprylic acid, capric acid, lauric acid, stearicacid, behenic acid, erucic acid, oleic acid, linoelic acid, or dimerizedderivatives thereof. HNPs are discussed in details in commonly owned,co-pending patent application Ser. No. 10/959,751, filed on Oct. 6,2004, which has been incorporated by reference above.

Thermosetting rubber may, comprise a reaction product of a cis-to-transcatalyst, a resilient polymer component having polybutadiene, a freeradical source, and optionally, a cross-linking agent, a filler, orboth. Preferably, the polybutadiene reaction product is used to form atleast a portion of the core of the golf ball, and further discussionbelow relates to this embodiment for preparing the core. Preferably, thereaction product has a first dynamic stiffness measured at −50° C. thatis less than about 130 percent of a second dynamic stiffness measured at0° C. More preferably, the first dynamic stiffness is less than about125 percent of the second dynamic stiffness. Most preferably, the firstdynamic stiffness is less than about 110 percent of the second dynamicstiffness.

The cis-to-trans conversion requires the presence of a cis-to-transcatalyst, such as an organosulfur or metal-containing organosulfurcompound, a substituted or unsubstituted aromatic organic compound thatdoes not contain sulfur or metal, an inorganic sulfide compound, anaromatic organometallic compound, or mixtures thereof. The cis-to-transcatalyst component may include one or more of the cis-to-trans catalystsdescribed herein. For example, the cis-to-trans catalyst may be a blendof an organosulfur component and an inorganic sulfide component.Suitable organosulfur compounds include those disclosed in U.S. Pat.Nos. 6,525,141, 6,465,578, 6,184,301, 6,139,447, 5,697,856, 5,816,944,and 5,252,652, U.S. App. Pub. 2004/0235587 and U.S. patent applicationSer. Nos. 10/882,130 and 10/959,751, the disclosures of which areincorporated by reference in their entireties.

More specifically, suitable organosulfur compounds include, but are notlimited to, pentachlorothiophenol, zinc pentachlorothiophenol, magnesiumpentachlorothiophenol, cobalt pentachlorothiophenol,pentafluorothiophenol, zinc pentafluorothiophenol, and blends thereof.Preferred candidates are pentachlorothiophenol (available from StrucktolCompany of Stow, Ohio), zinc pentachlorothiophenol (available fromeChinachem of San Francisco, Calif.), and blends thereof. Another groupof suitable organosulfur compounds are organic disulfides which include,without limitation, perhalogenated (i.e., fully halogenated) organicdisulfides and organometallic disulfides. Perhalogenated compounds arepreferably perfluorinated, perchlorinated, and/or perbrominated.Perhalogenated organic disulfides include perhalogenated derivatives ofany and all organic disulfides known and/or available to one skilled inthe art, which include those disclosed herein, such as ditolyldisulfides, diphenyl disulfides, quinolyl disulfides, benzoyldisulfides, and bis(4-acryloxybenzene)disulfide, among others. Aparticular example is perchloroditolyl disulfide. Organometallicdisulfides include combinations of any metal cations disclosed hereinwith any organic disulfides disclosed herein. A particular example iszinc ditolyl disulfide.

The organosulfur cis-to-trans catalyst, when present, is preferablypresent in an amount sufficient to produce the reaction product so as tocontain at least about 12 percent trans-polybutadiene isomer, buttypically is greater than about 32 percent trans-polybutadiene isomerbased on the total resilient polymer component. In another embodiment,metal-containing organosulfur components can be used according to theinvention. Suitable metal-containing organosulfur components include,but are not limited to, cadmium, copper, lead, and tellurium analogs ofdiethyldithiocarbamate, diamyldithiocarbamate, anddimethyldithiocarbamate, or mixtures thereof. Additional suitableexamples of can be found in commonly owned and co-pending U.S. Pat. App.Pub. 2003/0191246.

Suitable substituted or unsubstituted aromatic organic components thatdo not include sulfur or a metal include, but are not limited to,4,4′-diphenyl acetylene, azobenzene, or a mixture thereof. The aromaticorganic group preferably ranges in size from C₆ to C₂₀, and morepreferably from C₆ to C₁₀. Suitable inorganic sulfide componentsinclude, but are not limited to titanium sulfide, manganese sulfide, andsulfide analogs of iron, calcium, cobalt, molybdenum, tungsten, copper,selenium, yttrium, zinc, tin, and bismuth.

The cis-to-trans catalyst can also include a Group VIA component.Elemental sulfur and polymeric sulfur are commercially available from,e.g., Elastochem, Inc. of Chardon, Ohio. Exemplary sulfur catalystcompounds include PB(RM-S)-80 elemental sulfur and PB(CRST)-65 polymericsulfur, each of which is available from Elastochem, Inc. An exemplarytellurium catalyst under the trade name TELLOY and an exemplary seleniumcatalyst under the tradename VANDEX are each commercially available fromRT Vanderbilt.

A free-radical source, often alternatively referred to as a free-radicalinitiator, is required in the composition and method. The free-radicalsource is typically a peroxide, and preferably an organic peroxide.Suitable free-radical sources include di-t-amyl peroxide,di(2-t-butyl-peroxyisopropyl)benzene peroxide, 3,3,5-trimethylcyclohexane, a-a bis(t-butylperoxy) diisopropylbenzene,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, dicumyl peroxide,di-t-butyl peroxide, 2,5-di-(t-butylperoxy)-2,5-dimethyl hexane,n-butyl-4,4-bis(t-butylperoxy)valerate, lauryl peroxide, benzoylperoxide, t-butyl hydroperoxide, and the like, and any mixture thereof.

A cross-linking agent is included to increase the hardness of thereaction product. Suitable cross-linking agents include one or moremetallic salts of unsaturated fatty acids or monocarboxylic acids, suchas zinc, aluminum, sodium, lithium, nickel, calcium, or magnesiumacrylate salts, and the like, and mixtures thereof. Preferred acrylatesinclude zinc acrylate, zinc diacrylate (ZDA), zinc methacrylate, andzinc dimethacrylate (ZDMA), and mixtures thereof. The cross-linkingagent must be present in an amount sufficient to cross-link a portion ofthe chains of polymers in the resilient polymer component. This may beachieved, for example, by altering the type and amount of cross-linkingagent, a method well-known to those of ordinary skill in the art.

Suitable formulations for the cover layers of the multi-layer golf ballinclude, but not limited to:

(1) Polyurethanes, such as those prepared from polyols and diisocyanatesor polyisocyanates and those disclosed in U.S. Pat. Nos. 5,334,673 and6,506,851, U.S. patent application Ser. No. 10/194,059 and U.S. Pat.App. Pub. No. 2004/0010096;

(2) Polyureas, such as those disclosed in U.S. Pat. No. 5,484,870, U.S.Pat. App. Pub. 2003/0096936 and 2004/0010096; and

(3) Polyurethane-urea hybrids, blends or copolymers comprising urethaneor urea segments.

Polyurethane composition comprises the reaction product of at least onepolyisocyanate, at least one polyol, and at least one curing agent.Polyurea composition comprises the reaction product of at least onepolyisocyanate, at least one polyamine, and at least one curing agent.The curing agent can include, for example, one or more diamines, one ormore polyols, or a combination thereof.

Exemplary polyisocyanates include, but are not limited to,4,4′-diphenylmethane diisocyanate (“MDI”), polymeric MDI,carbodimide-modified liquid MDI, 4,4′-dicyclohexylmethane diisocyanate(“H₁₂MDI”), p-phenylene diisocyanate (“PPDI”), toluene diisocyanate(“TDI”), 3,3′-dimethyl-4,4′-biphenylene diisocyanate (“TODI”),isophoronediisocyanate (“IPDI”), hexamethylene diisocyanate (“HDI”),naphthalene diisocyanate (“NDI”); xylene diisocyanate (“XDI”);para-tetramethylxylene diisocyanate (“p-TMXDI”); meta-tetramethylxylenediisocyanate (“m-TMXDI”); ethylene diisocyanate;propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyldiisocyanate; 1,6-hexamethylene-diisocyanate (“HDI”);dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methylcyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of2,4,4-trimethyl-1,6-hexane diisocyanate (“TMDI”), tetracenediisocyanate, naphthalene diisocyanate, anthracene diisocyanate, andmixtures thereof. Polyisocyanates are known to those of ordinary skillin the art as having more than one isocyanate group, e.g., di-, tri, andtetra-isocyanate. Preferably, the polyisocyanate includes MDI, PPDI,TDI, or a mixture thereof, and more preferably, the polyisocyanateincludes MDI. It should be understood that, as used herein, the term“MDI” includes 4,4′-diphenylmethane diisocyanate, polymeric MDI,carbodiimide-modified liquid MDI, and mixtures thereof and,additionally, that the diisocyanate employed may be “low free monomer,”understood by one of ordinary skill in the art to have lower levels of“free” monomer isocyanate groups than conventional diisocyanates, i.e.,the compositions of the invention typically have less than about 0.1%free monomer groups. Examples of “low free monomer” diisocyanatesinclude, but are not limited to Low Free Monomer MDI, Low Free MonomerTDI, and Low Free Monomer PPDI.

The polyol component of the polyurethane can be polyester polyols.Suitable polyester polyols include, but are not limited to, polyethyleneadipate glycol, polybutylene adipate glycol, polyethylene propyleneadipate glycol, ortho-phthalate-1,6-hexanediol, and mixtures thereof.The hydrocarbon chain can have saturated or unsaturated bonds, orsubstituted or unsubstituted aromatic and cyclic groups.

Alternatively, the polyol component can be polycaprolactone polyols.Suitable polycaprolactone polyols include, but are not limited to,1,6-hexanediol-initiated polycaprolactone, diethylene glycol initiatedpolycaprolactone, trimethylol propane initiated polycaprolactone,neopentyl glycol initiated polycaprolactone, 1,4-butanediol-initiatedpolycaprolactone, and mixtures thereof. The hydrocarbon chain can havesaturated or unsaturated bonds, or substituted or unsubstituted aromaticand cyclic groups.

Additionally, the polyol component can be polycarbonate polyols.Suitable polycarbonates include, but are not limited to, polyphthalatecarbonate. The hydrocarbon chain can have saturated or unsaturatedbonds, or substituted or unsubstituted aromatic and cyclic groups.

The polyamine component of the polyurea can be amine-terminatedoligomers or polymers preferably having a molecular weight of at leastabout 200 and at least two primary or secondary amine terminal groupsper molecule. Because lower molecular weight amine-terminated polymersmay be prone to forming solids, a high molecular weight between about1,000 and about 5,000 is more preferred. Suitable examples ofamine-terminated oligomers or polymers include, but are not limited to:(a) amine-terminated polyethers, (b) amine-terminated polymers, (c)amine-terminated polycaprolactones, (d) amine-terminated polycarbonates,(e) amine-terminated polyhydrocarbons, (f) amine-terminated acidfunctional polymers, (g) amine-terminated polyolefins, (h)amine-terminated polyamides, (i) amine-terminated polyacrylics, and anycombination thereof.

Suitable examples of amine-terminated polyethers include, but are notlimited to polyoxyalkylene diamines, polyoxyethylene diamines,polyoxypropylene diamines, polyoxypropylene triamine,poly(tetramethylene ether) diamines, (ethylene oxide)-cappedpolyoxypropylene ether diamines, poly(triethyleneglycol) diamines,poly(trimethylolpropane) triamines,polyethyleneglycol-di(p-aminobenzoate),polytetramethyleneoxide-di(p-aminobenzoate), glycerin-based triamines,and the like.

Examples of other amine-terminated polymers, such as amine-terminatedpolyesters, amine-terminated polycaprolactones, amine-terminatedpolycarbonates, amine-terminated polyhydrocarbons, amine-terminated acidfunctional polymers, amine-terminated polyolefins, amine-terminatedpolyamides, and amine-terminated polyacrylics, preferably can beprepared from the above-listed hydroxyl-terminated polymers usingmethods described in U.S. Pat. App. Publication 2002/0132915 by Pantoneet al., which is incorporated by reference in its entirety. Thesemethods include, for example, (1) reductive amination of polyetherpolyols with ammonia and hydrogen in the presence of a catalyst (U.S.Pat. Nos. 5,015,773, 5,003,107, and 3,654,370), (2) hydrogenation ofcyanoethylated polyols, (3) amination of polyol/sulfonic acid esters(U.S. Pat. No. 3,236,895), (4) reacting polyols with epichlorohydrin anda primary amine, or (5) those listed in the publication “Jeffamine,Polyoxypropylene Amines” by Texaco Chemical Co., 1978.

The curing agent may include a polyol curing agent. Suitable polyolcuring agents include, but are not limited to, ethylene glycol,diethylene glycol, polyethylene glycol, polyethylene propylene glycol,polypropylene glycol, lower molecular weight polytetramethylene etherglycol, 1,3-bis(2-hydroxyethoxy)benzene,1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene,1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, resorcinol-di-(β-hydroxyethyl)ether,hydroquinone-di-(β-hydroxyethyl)ether, trimethylol propane, or mixturesthereof.

Polyamine curatives are also suitable for use in the curing agent of thepolyurethane composition and have been found to improve cut, shear, andimpact resistance of the resultant balls. Preferred polyamine curativesinclude, but are not limited to, 3,5-dimethylthio-2,4-toluenediamine andisomers thereof; 3,5-diethyltoluene-2,4-diamine and isomers thereof,such as 3,5-diethyltoluene-2,6-diamine;4,4′-bis-(sec-butylamino)-diphenylmethane;1,4-bis-(sec-butylamino)-benzene; 4,4′-methylene-bis-(2-chloroaniline);4,4′-methylene-bis-(3-chloro-2,6-diethylaniline);polytetramethyleneoxide-di-p-aminobenzoate; N,N′-dialkyldiamino diphenylmethane; p,p′-methylene dianiline (“MDA”); m-phenylenediamine (“MPDA”);4,4′-methylene-bis-(2-chloroaniline) (“MOCA”);4,4′-methylene-bis-(2,6-diethylaniline);4,4′-diamino-3,3′-diethyl-5,5′-dimethyl diphenylmethane;2,2′,3,3′-tetrachloro diamino diphenylmethane;4,4′-methylene-bis-(3-chloro-2,6-diethylaniline); trimethylene glycoldi-p-aminobenzoate; and mixtures thereof. Preferably, the curing agentof the present invention includes 3,5-dimethylthio-2,4-toluenediamineand isomers thereof, such as ETHACURE 300. Suitable polyamine curatives,which include both primary and secondary amines, preferably have weightaverage molecular weights ranging from about 64 to about 2000.

Other than in the operating examples, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentagessuch as those for amounts of materials, and others in the specificationmay be read as if prefaced by the word “about” even though the term“about” may not expressly appear with the value, amount or range.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the specification and attached claims are approximationsthat may vary depending upon the desired properties sought to beobtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

While it is apparent that the illustrative embodiments of the inventiondisclosed herein fulfill the preferred embodiments of the presentinvention, it is appreciated that numerous modifications and otherembodiments may be devised by those skilled in the art. Examples of suchmodifications include slight variations of the numerical valuesdiscussed above. Hence, the numerical values stated above and claimedbelow specifically include those values and the values that areapproximately or nearly close to the stated and claimed values.Therefore, it will be understood that the appended claims are intendedto cover all such modifications and embodiments, which would come withinthe spirit and scope of the present invention.

1. A multi-layer golf ball comprising at least two adjacent layers,wherein one of the layers comprises a plurality of metal materialsusceptors, wherein the susceptors improves the adhesion between the atleast two adjacent layers when exposed to induction heating, and whereinthe susceptors are contained in a continuous mesh in the form of apolygon.
 2. The golf ball of claim 1, wherein the polygon is a memberselected from the group consisting of triangle, square, pentagon,hexagon, and quadrilateral.